Saturday, March 3, 2012

March Long Range Severe Weather Outlook

What the landscape may look like as a storm system enters the West Coast.
I am sending out a message of warning to those in the Plains for the next few weeks to be on the lookout.

A vortex will soon be forming in Alaska. This vortex of low pressure will act as a breeding ground for storm systems. The storm systems will come onshore the US and follow the jet stream north into the Canada/US border.

The jet stream will be displaced north into the Canada/US border as a cause-effect relationship between the Alaskan Vortex and a ridge in the Central and Eastern US.

As a system comes onshore, it will try to push eastward instead of northeast, pressing down on the jet stream and creating higher wind speeds in the jet stream as a result. As the system moves along the jet stream, the back end of it will carry cold, dry air from the Mountains. Out in front of the storm system will be moist, unstable Gulf of Mexico air.

At some point, the cold air will clash with the warm air, igniting thunderstorms that will likely start out as discrete super cells forming in the midst of the warm, humid air out ahead of the system. These storm cells may have rotation, thanks to the jet stream. Eventually, these storm cells would become linear as a cold front traverses across the Northern US with the severe storms.

I'm not saying this will happen with every storm, but as of now that is how things are looking.
Something I am seeing in the most recent 12z GFS run is how a storm is down in the South US, but the jet stream is not latching on to it. I feel that the GFS is incorrectly interpreting that situation.

Here are two scenarios for what could happen. The first is the light blue storm track, which rides along the jet stream and may produce severe storms south of it (light red).

The second track is if the jet stream is too far north so the system meanders along the Gulf Coast, wrapped up in warm, unstable Gulf air. The entire Southeast and South Plains are taken ahold of severe storms in that situation.

Again, this is very long range and may not happen at all- it is a mere representation of what has recently been shown and put together with some of my forecasting.


Indndawg said...

Andrew, need you input on Thur-Fri time frame. I live near Tupelo MS and I coach h/s tennis. We have a major match Thur aft. 12z GFS says rain may hold off...ECMWF seems more progressive.What say you?

Andrew said...

It's probably going to be pretty dicey. The GFS has not been handling timing well recently, but the event is still pretty long range.

ERN WX said...

Agreed, Andrew. Gfs has not been doing to great lately with timing. The 12z Euro keeps on wanting to bring a decent shot of cold air. Tomorrow morning my area may get a little snow. A bit goofy after 57 for the high today! The same areas that were hit hard by tornadoes yesterday may get some snow. The pattern is interesting. Next winter will be better. Very well written article!!! Thanks again!!!

ERN WX said...

100 tornadoes SPC says. Rough outbreak. My thoughts and prayers go out to those who were affected by the t-storms.

Anonymous said...

Notice how all of tornado alley is covered. This post isn't really a forecast, it's just showing how tornado alley works. Some systems go north, some go south. He's just saying how, like what normally happens in March, the alley will begin to heat up.

Anonymous said...

Hey Andrew, why do you use the term "Mobile Storm Track TEAM" when there is only one writer for this blog (yourself)?

Andrew said...

Eastern WX: Yeah, this was a pretty horrible event.

Anonymous #1: It is indeed a forecast- it unintentionally happened to turn out covering much of tornado alley. I didn't even recognize it until you mentioned it.

Anonymous #2: It's one of those things that make this blog sound like it has more than one person (example, I unintentionally use 'we' a lot in my posts).